My BLOG about my journey into the invisible world of ultraviolet UV photography, simulated bee, butterfly and animal vision photography and the special lenses, filters and lighting needed to make it work - also in HD video + 3D stereo.

Thursday, December 29, 2011

There will be a new major BBC 3x 60min series, produced by BBC Scotland which will be aired on BBC TWO most likely in spring 2012. The current working title of the series is "Green Planet" and it will be presented by geologist and Professor Iain Stewart.

[click on image to see a larger one]

(c) BBC London

My UV part will be shown in the "The Science of Plants" section. So what you'll see will be some of my recent work, for instance Rudbeckia

as well as Hemerocallis, Zinna and Bidens, just to name some.

As soon as I know more details or have the schedule when this will be aired on BBC TWO, I'll let it know here.

Sunday, December 25, 2011

A good friend sent a wonderful Christmas Bouquet which also included deep red Hippeastrum (Amaryllis) blossoms, I have already published about it here on my BLOG. Now UV closeups of that one, shot using a UV-Planar 60mm and my UV sensitive camera. Filter used for the reflected UV shots was the Baader-U filter and a modified high power Xenon flash served as light source.

[click on image to see a larger one]

Closeup including stigma and stamen:

the petal surface:

an finally the glowing stigma:

Doesn't that look like "pure amethyst"?

Impressive how much such a beautiful Christmas Gift may reveal, even if it is invisible to our human eyes...

Saturday, December 24, 2011

A good friend sent a wonderful Christmas Bouquet - so here it is as it looks like in reflected ultraviolet light. It was shot using my UV sensitive camera and a Noflexar 35mm lens. Filter used for the UV shot was the Baader-U filter and a modified high power Xenon flash was the light source used.

Friday, December 23, 2011

This is about Hippeastrum or as it is called here, Amaryllis, usually sold around Christmas time. It was shot using my UV sensitive camera and a Cerco 94mm lens. Filter used for the UV shot was the Baader-U filter and a modified high power Xenon flash served as a light source.

Friday, November 25, 2011

Here some test results using the Staeble Lineogon 3.5/35mm lens for reflected UV photography, as well as for IR after having done some successful transmittance tests as shown here on my BLOG

VIS:

UV:

VIS-UV differential:

IR:

VIS-IR differential:

UV-IR differential:

[please ignore the shadow image in the last three images caused by ND+IR stacked filters, this is unrelated to the lens performance]

In summary one could say that the lens performs quite well; there is some focus shift, but rather small. No wonder actually, since Stable was the subcontractor of Novoflex, so the Noflexar 3.5/35mm and the Lineogon 3.5/35mm share the same optics based on my research. The mechanics are different though, as the Lineogon has a quite smaller barrel and also lacks the close-up focusing mechanism teh Noflexar is so famous for. It also has a M39 thread mount, but not a Leica register, as it once was made for the Braun PAXETTE camera, having a 44.0mm register.

I conducted a test today to measure the UV transmittance of some older manual focus lenses I had sitting around, all f = 35mm and all having either M39mm or M42mm thread mount, so may easily be adapted onto modern DSLR's, if their back focal length fits the camera register.

Be reminded that this is only a test of the suitable UV transmittance, not of other important parameters for UV photography (sharpness, contrast, freedom of flare or hotspots etc.)

Of course the well known Novoflex Noflexar 35mm stands out as a very well transmitting lens and it is actually not a surprise that the Staeble Lineogon does about equally well - it is the same optics inside as Novoflex subcontracted to the German company Staeble to design their optics, which my own research concluded. Be reminded that the Lineogon was made for the PAXETTE camera with M39 thread mount, but for a 44mm register (so is NOT Leica compatible, but helps to adapt as it allows for 15mm more space).

Friday, November 18, 2011

I noticed that I haven't published a test of the 2" Andrea-U filter I had bought beginning of May 2011, so here it is. It is sold under the moniker "Andrea-U filter", like Baader sells his as "Venus-Filter".

A first comparison of the uncoated 2.05mm thick Andrea-U filter with the Baader-U2 filter (2", new type) brought the following results:

I) Transmittance

A spectral scan results in the following transmittance graph (@ zero and 45 degrees angle of light):

The results of the Baader-U2 filter is also shown, to be able to compare both filters. Andrea-U has some leakage into the violet/deep blue to about 410nm, but there is no sign of IR-leakage (up to 850nm).

The resulting Andrea-U image has an exposure which is about 1/4 stop less that that of the Baader-U2. There is no sign of IR-leakage (up to 850nm); the somewhat warmer tone of the middle image was caused by the special palette used. All images were processed identically otherwise.

III) Summary

The Andrea-U filter is mechanically well made (the description is printed on foil and taped on the rim, which might eventually come off after long use - I would have preferred it printed or engraved of the metal, but that would certainly have increased cost).

Personally I would rate it a quite useful filter for the 375nm range, especially if used with older "normal" UV transmitting lenses since in the 375-400nm range it has a higher transmittance as the Baader-U2 filter (25% higher = 0.5EV at 390nm).

IV) Incorrect maker statements

The maker of the Andrea-U filter states that "The leading Venus filter (i.e. the Baader-U filter) is a dichroic filter" which is not correct. It is further stated that "This sensitivity to the angle of incidence (AOI) of the light results in some ultraviolet light being rejected that should have passed to the sensor... in other words, a false representation of the object being photographed in the ultraviolet is created." Also that statement is not correct and I will in the following course prove why:

The Baader U filter is an ionic colored filter that defines its properties mainly and it has a two sided dichroic overcoating that only has to block unwanted VIS and NIR leakage. I measured the Baader-U filter at 0-degrees and 45-degrees and my findings were 1) a decrease in transmission of about 0.2 stops (that effect also any pure ionic colored filter has (I show UG11 as an example and also show that under I) above for the Andrea-U filter), as the transmitting light has to pass simply a thicker glass passage - although the Andrea-U filter also shows that effect, it is not mentioned on the maker's site) and 2) a widening of the FWHM of about 12nm.

Both results are irrelevant for practical photographic work based on my experience.

I don't understand why these possibly misleading statements were made by the maker, as his Andrea-U filter is a good one and certainly finds a use for reflected UV photography. But I leave any interpretation of that to the interested reader...

Tuesday, November 8, 2011

Also took a few shots today on a dull+gray day using another famous and quite rare rangefinder lens, a Canon f3.5 / 25mm Topogon clone designed by Mukai Jirō in 1956 with Leica thread mount (LTM 39mm x 26tpi) with a diagonal angle of view of 82° (on full format). My friend Marco Cavina has a very good article about those lenses based on the TOPOGON design HERE .

These Topogon clone lenses are all successors of the famous HYPERGON lens designed by Emil von Hoegh around 1900.

Shots were done @f8 and ISO640 on my UV sensitive camera.

[click on image to see a larger one]

Left VIS, right UV (bw) 100% center crop:

Left VIS, right IR (bw) 100% center crop:

Now color differentials (full format) to make focus shift visible:

VIS-UV:

VIS-IR:

IR-UV:

As you see, there is some small focus shift (UV and especially IR image show slight back focus), but nothing dramatical (focus was not touched, the shift could be calibrated of course). Interestingly enough, there is only a very small shift between UV and IR (a 695LP filter was used), but overall the IR shift is much larger than the nearly neglectable one for UV (Baader-U filter was used).

In terms of exposure, the one for UV was -7.7EV as compared to the VIS shot, whereas the one for IR was the same as for VIS. All shots (VIS, UV, IR) needed identical exposure correction (+2/3 stop) for a proper exposure using A mode.

Here now closeups using one of my last Rudbeckias. Distance between lens and flower was about 100mm (using a thin helicoid for closer focusing, as with most rangefinder lenses, the closest focusing distance is one meter):

VIS:

UV:

IR:

Not that bad actually also that lens ;)

That Canon 3.5/25mm transmits UV to about 350nm, but the UV shot above was taken using the calibration of a flat transmitting quartz fluorite lens, to show the effect also in the resulting color. A color calibration could have been done also for that lens.

Took a few shots today on a dull+gray day using a very small and lightweight russian rangefinder lens, an Orion-15 f6/28mm Topogon clone with Leica thread mount (LTM 39mm x 26tpi) with a diagonal angle of view of 75° (on full format). My friend Marco Cavina has a very good article about that lens HERE including quite surprising photographic comparisons with much more expensive Leica lenses.

These Topogon clone lenses are all successors of the famous HYPERGON lens designed by Emil von Hoegh around 1900.

Shots were done @f8 and ISO640 on my UV sensitive camera.

[click on image to see a larger one]

Left VIS, right UV (bw) 100% center crop:

Left VIS, right IR (bw) 100% center crop:

Now color differentials (full format) to make focus shift visible:

VIS-UV:

VIS-IR:

IR-UV:

As you see, there is some focus shift (UV + IR image show slight back focus), but nothing dramatical (focus was not touched, the shift could be calibrated of course). Interestingly enough, there is only a very small shift between UV and IR (a 695LP filter was used), but overall the IR shift is larger than that for UV (Baader-U filter was used).

In terms of exposure, the one for UV was -7.3EV as compared to the VIS shot, whereas the one for IR was the same as for VIS. All shots (VIS, UV, IR) needed identical exposure correction (+2/3 stop) for a proper exposure using A mode.

Here now closeups using one of my last Rudbeckias. Distance between lens and flower was about 150mm (using a thin helicoid for closer focusing, as with most rangefinder lenses, the closest focusing distance is one meter):

VIS:

UV:

IR:

Not that bad actually ;)

That Orion-15 transmits UV to about 350nm, but the UV shot above was taken using the calibration of a flat transmitting quartz fluorite lens, to show the effect also in the resulting color. A color calibration could have been done also for that lens.

A downside should be mentioned: that lens has a 40.5mm deep set front filter thread that does not allow step rings to be mounted, so some clever idea how to attach filters is called for...

Friday, October 28, 2011

I have this lens since quite a while but never really thought it would be useful for UV or IR due to its complex lens design incorporating lots of glass elements and a few cemented ones, based on the famous Biogon design of Dr Bertele. But well, I'm too much a curious engineer, so while I was digging through lenses, I thought, I should convert it and give it a chance...

Actually that lens design was developed and used long time as their (former GDR) best wide angle lens, used for their "Reihenmesskammer" for aerial reconnaissance. This lens here is a derivative of its larger brother, with an reduced image angle and most likely a symmetrical 8e/4g design.

Wednesday, October 19, 2011

It turned out that it seems to be a quite useful lens for VIS and now also IR on my UV camera(s), although it has quite some focus shift also in IR (expected from that simple design). The focal length has been confirmed by further measurements to be around 25 - 26mm, so let's stay with 26mm.

Wednesday, October 12, 2011

I found and adapted a previously unknown (in that focal length) ultra wide angle large format lens, obviously a Hypergon design, which Emil von Höegh invented around 1900 for the GOERZ company [he also invented the famous DAGOR lens for them] which was later taken over by ZEISS. Based on that Hypergon design, Robert Richter later in 1934 developed the famous TOPOGON lens for ZEISS, which became the classic aerial imaging lens for quite some time. The earlier Hypergon I have here was made approx. 1950 I would guess with a diagonal angle of view of about 120° (on its designed format of about 145mm image circle).

It turned out that it seems to be a quite useful lens for VIS and UV on my UV sensitive cameras, although it has quite some focus shift in UV (expected from that simple design). The focal length is an estimate, it is somewhere between 24 - 26mm from my measurements. I show the lens aberrations in the following screenshot (scaled to fit that smaller sensor, hence smaller used image angle and object at infinity; for an f11 aperture, which is the optimum for that lens):

About Me

This is my blog about my film and photographic work in 3D, ultraviolet UV, infrared IR and fluorescence using special lenses and equipment. All text and images carry my copyright and I do not allow to link to or copy / download from my site or any parts thereof without my prior permission.
email me in case of questions or interest in my images (esp. for non-profit orgs) or if you need a complete camera + lens + filter + light set for UV photography:
postmaster AT macrolenses.de